INVESTIGATIONS OF CHEMICAL INTERACTION BETWEEN BI-BASED 2212 AND (RE)BA2CU3O7 HIGH T(C) SUPERCONDUCTING MATERIALS

Composite materials have been synthesized by mixing 90% (or 95%) YBa2C u3O7 and 10% (or 5%) Bi2Sr2Ca1Cu2O8 by weight, and firing at 900-degre es-C to promote grain growth by inducing a liquid phase (Bi2Sr2Ca1Cu2O 8) in the system. The influence of the amount of liquid phase on the X -ray diffraction data and electrical properties is reported. Energy di spersive X-ray (EDX) analyses are also reported. The YBiBa2O6 phase is formed during the heat treatment and introduces additional chemical h eterogeneities at the grain boundaries. A previously reported 2212-rel ated superconducting phase, Bi2(Sr,Ba)2(Ca,Y)Cu2O8+y, could also be fo rmed during the synthesis process, and its effect on the electrical re sistance versus temperature measurements is discussed. Attempts to sub stitute RE ions (Dy3+, Er3+, Ho3+) for Y3+ in YBiBa2O6 have been succe ssful and are reported in an appendix section. X-ray diffraction data are also reported. EDX analyses have been performed specifically for a typical ErBiBa2O6 compound and reveal the presence of a new Er2Ba4O7 phase.